Method of operating a spark ignition internal combustion engine and compositions therefor



1958 J. B. HINKAMP ET AL 2,855,905 METHOD OF OPERATING A SPARK IGNITION INTERNAL COMBUSTION ENGINE AND COMPOSITIONS THEREFOR Filed July 21, 1955 THEORIES OF BROMINE O O.| 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 L0 l.l L2

THEORIES OF CH LORINE JAMES B. HINKAMP, JOEL A. WARREN, INVENTORS BYw W Unite METHOD OF OPERATING A SPARK IGNITION INTERNAL (IQMBUSTION ENGINE AND COM- POSITIONS THEREFOR Appiication July 21, 1955, Serial No. 523,563

Claims. (Cl. 123--1) This invention relates to a method of operating a sparkignition internal-combustion engine and to compositions particularly useful in conducting this method.

The operation of spark-ignition internal-combustion enginesOtto-cycle engines-on leaded fuels gives rise to a number of well-recognized problems. The use of organic halides in conjunction with tetraethyllead satisfactorily overcomes one such problem, namely, excessive deposition of lea-d salts on spark plugs and exhaust valves which would otherwise interfere with engine operation. The use of halogen scavengers, however, aggravates another problem which is variously termed surface ignition, wild ping, preignition, etc. This problem results from the catalytic activity of residual lead salts in promoting the oxidation of organic matter in the engine deposits. Under certain conditions this oxidation produces sufficient heat in a localized area to prematurely ignite the fuel-air mixture during the intake or compression stroke of the engine cycle. This premature ignition subjects the end-gas to more severe conditions of temperature and pressure than would otherwise be encountered and often results in end-gas detonation. Lead salts which contain chlorine and/or bromine are superior catalysts to the lead salts which form in the engine when chlorine and/or bromine are not present. Consequently, the established use of halides as scavengers for the tetraalkyllead antiknock agent increases oxidation catalysis and thus augments the seriousness of the surface-ignition problem.

A method of operating a spark-ignition internal-combustion engine and compositions used according to this method have now been found which effectively control surface ignition. The aspects of the present invention now to be considered also provide other important benefits, including (1) engine deposit weight reduction, (2) reduction in octane requirement increase, (3) increased exhaust valve life, (4) smoother engine operation with substantial decrease in engine noise and roughness and (5) more eificient engine operation, that is, greater economy of operation.

An object of this invention is to provide a method of operating a spark-ignition internal-combustion engine to substantially alleviate the surface-ignition problem.

Another object of this invention is to provide compositions to be employed in the above-mentioned method, which compositions enable the attainment of substantial reduction in surface-ignition rate. Another object of this invention is to provide a method and compositions of matter which concurrently alleviate the surface-ignition problem and result in the important benefits enumerated above. Other important objects of this invention will be apparent from the ensuing description.

It has now been found that the above and other objects of our invention are accomplished by the method of operating a spark-ignition, internal-combustion engine on a gasoline containing an antiknock quantity of a tetraalkyllead antiknock agent and a mixture of a bromine- States Patent 0 7 2,855,905 Patented Oct. 1 195% ice containing scavenger and a chlorine-containing scavenger with the particular improvement comprising (I) the mixture of bromineand chlorine-containing scavengers which is introduced into the combustion chamber initially being present in the gasoline in proportions which are defined by the area ABCD of the figure, and (II) concurrently'introducing into the combustion chamber of the engine a small amount of a wholly distilled crankcase lubricating oil distilling within the range of from about 550 to about 900 F. (extrapolated to atmospheric pressure) according to ASTM Test Procedure D-l-52T.

A preferred method of this invention comprises introducing into a combustion chamber of an operating sparkignition internal-combustion engine (I) gasoline containing an antiknock quantity of a tetraalkyllead antiknock agent and a mixture of a bromo hydrocarbon scavenger and a chloro hydrocarbon scavenger, said scavengers being capable of reacting with the lead during combustion in the engine to form volatile lead halides, the proportions of bromine and chlorine of said mixture initially being defined by the Area ABCD of the figure, and (II) a small amount of a wholly distilled crankcase lubricating oil as defined above. A particularly preferred method of this invention comprises the method as described above in which the mixture of bromohydrocarbon scavenger and chlorohydrocarbon scavenger is a mixture of ethylene dibromide and ethylene dichloride, the proportions of bromine and chlorine of this mixture being defined by ABCD of the figure.

According to this invention substantial improvements in engine performance are brought about by a combination of novel scavenger proportions and the use of particular lubricating oils in conjunction therewith. The nature of the scavenger proportions of this invention is shown in the figure. This figure represents relative proportions of bromine and chlorine scavengers which are used to obtain substantial benefitst in engine performance, particularly marked reduction in surface-ignition rate. In this figure the ordinate is theories of bromine and the abscissa is theories of chlorine. The terms theories of bromine" and theories of chlorine have established meansings in the art. According to established usage a theory of bromine is defined as the quantity of bromine theoretically required to react with the lead to form PbBr i. e. two atoms of bromine per each atom of lead. In like fashion, a theory of chlorine is the amount of chlorine theoretically required to react with the lead to form PbCl or two atoms of chlorine per each atom of lead.

In the figure the area ABCD defines the relative proportions of bromine and chlorine which are present in the form of a mixture of bromine-containing scavenger and chlorine-containing scavenger. These proportions are based upon the amounts of lead present in the fuel or antiknock fluid-in the form of a tetraalkyllead antiknock agent. Area ABCD, therefore, is obtained by connecting with straight lines the individual relative proportions represented by points A, B, C and D. The relative proportions of these four points are shown in Table Area EFGH of the figure represents novel relative proportions of bromine and chlorine which bring about a particularly high degree of effectiveness in the reduction of surface ignition commensurate with other engine factors, such as lash loss in the valve train. T hus'the proportions as defined by area EFGH are preferred. The individual proportions of bromine and chlorine used to define area EFGH are as shown in Table II.

The benefits of this invention can be achieved by the use of proportions of bromine and chlorine as defined by areas ABCD, and preferably EFGH, with any mixture of bromine-containing scavenger and chlorine-containing scavenger. That 'is, an important feature of this invention is that the unexpected results obtained therefrom are directly attributable to the relative proportions of the active scavenging ingredients of the mixed Sm engerthese active scavenging ingredients being the bromine and chlorine contained in the scavenger mixture. The remainder of the molecule of each of the ingredients of the scavenger mixture is, for the purposes of this invention, a suitable carrier for these halides. The selection of the particular scavengers used in formulating the antiknock fluids and antiknock fuels used according to this invention thus is largely a matter of choice. Of course, scavengers differ in many respects such as in scavenging effectiveness, stability characteristics, solubility and inductibility standpoints and cost. On the basis of these factors it is preferable to employ mixtures of bromohydrocarbon and chlorohydrocarbon scavengers, notably ethylenedibromide and ethylene dichloride.

To understand the fact that a mixture of any suitable bromine-containing scavenger and chlorine-containing,

scavenger can' be employed to obtain the benefits of invention, the fundamental nature ofthemode of operability of the invention'isconsidered. In essence thej'in vention involves theetfect of novel fuel and oil relation;

ships on the composition of engine deposits, particularly combustion-chamber deposits which are largely responsible for the surface-ignition problem. Despitel the substantial advances made in the scavenger art, no scavenger.

has yet been produced, which can completely. eliminate.

engine deposits. brorni'neandchlorinecontaining scavengers are used, the residual engine deposits always contain lead salts containing bromine and chlorine. Ac-

cording to this. invention these 'residual engine deposits' are beneficially modifiediby the 'use of certain relative proportions of these active scavenging ingfedientsbromine and chlorinef-and by the ,ernploym entof certain whollydistilled' crankae. lubricatingoils. Thus,

once the flame front haspass'ed through the combustion.

chamber initially containing. the environment produced according tothis invention, the bromine and chlorine scavengers, irrespective offtheir. initial; character, are changed by combustion into' complex. lead salts, con? containing bromineand'chlo'rine'. can" rr ently, thedecomposition of the wholly"distilledcrankcase lubricating oil produces organic decomposition products, a portion,

of which remain in the combustion chamber. Thus, a

novel type of enginedepos'its 'isfori'nediandj these engine,

deposits have been hQWn to result in 'a considerably lower rate of surface ignition as compared to engine deposits which are formed during conventional engine operation. Therefore, the chief requirement. of the bromine-containing and chlorine-containing scavengers is that they be capable of reacting with the leadduring .com-.

bustion in the engine to form volatile lead salts contain- The Wholly-distilled crankcase lubricating oil used in this invention must distill within the range of from about 550 to about 900 F. (extrapolated to atmospheric pressure) according to ASTM Test Procedure D-l-52T. This test procedure may be found in ASTM Standards on Petroleum Products and Lubricants, 1954. This lubricating oil is preferably derived from petroleum crude oil because of the beneficial manner in which whollydistilled crankcase lubricating oils of petroleum origin are burned during engine combustion. It has been found that such lubricating oils once ignited and consumed in the combustion chamber leave an organic residue which cooperates with the products of combustion from the novel fuels used in this invention to form engine deposits which promote better engine performance than ordinary engine deposits.

As used in the specification and claims the phrase wholly-distilled crankcase lubricating oil means that the lubricating oil is free from bright stock. An essential feature of this invention is that the lubricating oil used must be essentially free from bright stock because the presence of more than trace amounts of bright stock, which is a relatively non-volatile hydrocarbon fraction of high viscosity, results in a deleterious effect upon the engine depositsand produces markedly inferior results on the rate of surface ignition. It is well known in the art that bright stock is not present in a wholly-distilled crankcase lubricating oil.

The above defined wholly-distilled crankcase lubricating oil is introduced into the combustion chamber in small amounts by one or more methods. The preferred method of introducing small. amounts of this oil is introduction via normal oil-consumption channels such as piston ring and valve guide by-pass. In this manner, the requisite amount of oil is substantially.- continuously introduced into the combustion chamber. The amount of such oil which is introduced into the combustion chamber depends upon thecondition of the engine, the viscosity of the oil, the. engine; operating conditions and the nature of the engine itself. Generally speaking, good results are achieved under normal engine-operating conditions with the average spark-ignition internal-combustion engine, if from about 0.5 to about 8 milliliters of the oil are introduced into each combustion chamber per hour of operation. It is preferable that the oil be introduced into each cylinder of the engine at, the rate of from about 1 to about; 6 milliliters per hour ofengine operation.

Another way of introducing the above-defined lubricating oibintothe combustion chamber of the engine is by blending a sufiicient amount of the oil with the gasoline. This gasoline is then used in conjunction with a whollydistilled oil as defined above as crankcase lubricant. By so. doing the introduction of the oil is accomplished by carburetion and manifolding as well as by normal oilconsumption channels. Another advantage of having the wholly-distilled oil dissolved in the gasoline is that this. oilnot only beneficially modifies the combustion process. according to this invention, but also acts as an upper-cylinder lubricant.

Another method of introducing the above described lubricating oil'into the combustion chamber of the engine is by means.- of supplementary injection devices. These devicesmay be attached to theengine and adjusted so as to introduce the proper quantity of the oil into the combustion chamber in a more or lesscontinuous manner. According to thismethod the crankcase lubricant is a wholly-distilled oil having the characteristics set forth above. Thus the leaded gasoline containing the scavenger proportions of this invention is ignited inthe presence of such wholly-distilled oil even if the crankcase oil consumption of the engine islow,

To illustrate an embod.'n1 ent of the present invention and the greatly superior results: obt-inedthereby, an ex tensive series o f engine testswas conducted. A standard parkz spit w mflti'e ltw l vsti n; n ne perate The fuel used in these engine tests was a commercially available blend of straight-run, catalytically-cracked and polymer blending stocks. This gasoline contained 3 milliliters of tetraethyllead per gallon as the antiknock agent.

The engine was equipped with an extra spark plug installed in a center opening of the cylinder head. This spark plug was used as an ionization gap. A mechanical breaker switch driven at camshaft speed was also provided. This breaker was open for 80 crankshaft degrees between 70 before top dead center (BTC) and after top dead center (ATC) During normal combustion with ignition timing at top dead center (TDC) the normal flame front reached the ionization gap to 18 ATC during the period when the points were closed and no count of this normal ignition was made. When an erratic or early flame front reached the ionization gap during the above open period the flame activated this gap and this activation was recorded by an electronic surface-ignition counter.

In one series of tests the scavenger complement of the above leaded gasoline consisted of a prior art mixture of 0.5 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride. The proportions of this scavenger complement constitutes a preferred embodiment of the invention disclosed and claimed in U. S. Patent 2,398,281. The crankcase of the test engine contained a phenol-treated, mixed-base mineral oil having a viscosity of 374 Saybolt Universal seconds (SUS) at 100 F. and 58.4 SUS at 210 F. The viscosity index (VI) of this oil was 107. This oil was a representative bright stock-containing crankcase lubricating oil.

In another series of engine tests the identical test procedure including gasoline, lead content and lubricating oil factors was used. The one difference in this instance was that the scavenger complement was a mixture of 0.6 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride. This scavenger mixture falls on the line CD of the figure. However, this series of tests was not run in accordance with the present invention since the lubricating oil was a bright stock-containing oil rather than a wholly-distilled oil.

In a third series of tests conducted in the manner as described above the scavenger complement employed consisted of 0.5 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride. The crankcase lubricating oil was free from bright stock-i. e. the lubricating oil was a mixed-base, solvent-extracted whollydistilled crankcase oil having a viscosity index of 135.7, a pour point of 25 F., a viscosity at 100 F. of 249.5 SUS and a viscosity at 210 F. of 55.2 SUS.

Still another series of engine tests was conducted, this series being representative of the method of this invention. The scavenger complement consisted essentially of 0.6 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride. The crankcase of the engine contained the wholly-distilled crankcase lubricating oil as described in connection with the next preceding series of tests.

In each individual test of the foregoing series of engine tests, the engine Was operated for 165 hours and the rate of surface ignition determined. The rate of oil consumption was from 1 to 6 milliliters of oil per hour of engine operation in each test.

The results of the above-described series of engine tests are shown in Table III.

TABLE III Relative surface ig= nition rate Whollydistilled oil Scavenger contg. oil

theory of bromine and 1.0 theory of chlorine! 32 0.5 0.6 theory of bromine and 1.0 theory of chlorine.-..

From the data in Table III several conclusions are evident. First, the increase inbromine concentration from 0.5 to 0.6 theory produces no benefit when the crankcase oilintroduced into the combustion chamber is a bright stock-containing lubricating oil. In fact, the rate of surface ignition was increased by 29 percent with this fuel-oil combination. Second, benefits are achieved from the standpoint of reduction in surface ignition when the lubricating oil introduced into the combustion chamber of the engine is a wholly-distilled crankcase lubricating oil. The third and-most significant conclusion from the above engine tests is that the degree of reduction in surface ignition brought about by the use of a wholly-distilled oil instead of a bright tock-containing oil is much greater when the proportions of the scavengers are as defined by the figure. Thus, while the wholly-distilled lubricating oil reduced the surface ignition rate using the scavenger proportions of 0.5 theory of bromine and 1.0 theory of chlorine by 50 percent, the corresponding reduction when the scavenger proportions were 0.6 theory of bromine and 1.0 theory of chlorine was 75 percent. Moreover, the series of engine tests conducted according to this invention resulted in an overall reduction in surfacedgnition rate amounting to 68 percent as compared to the results obtained using a preferred scavenger mixture as described in U. S. Patent 2,398,281 in conjunction with a bright stockcontaining oil. Thus the results obtained by the practice of this invention are very unexpected since the use of 0.6 theory of bromine and 1.0 theory of chlorine with a bright stock-containing oil actually increased surface-ignition rate as compared to 0.5 theory of bromine and 1.0 theory of chlorine using the same oil.

The results described in the above series of engine tests are illustrative of the benefits obtainable by the practice of this invention. The method and compositions of this invention were tested in a variety of spark-ignition internal-combustion engines including modern passenger cars operated on the road. Consideration will be given to results obtained by operating one make of passenger car on the road under moderately low-speed driving conditions.

The cars used in this series of tests had modern V-8 overhead-valve engines with a compression ratio of 9.0 to 1. These cars were operated over a fixed test route under a moderately low-speed, metropolitan-area driving schedule. The test route was a 55-mile loop through urban and suburban areas, over which 3540 miles per hour road speed was maintained for 65 percent of the time. A series of 42 trafiic stops, with moderate accelerations and decelerations made up the balance of the test cycle. These tests started with selected new spark plugs, clean combustion chambers, induction systems, and crankcases, and calibrated carburetors and distributors.

The cars were operated for about 3,000 miles using different test fuels and different lubricants. Some of the vehicles were operated according to the method of this invention whereas other vehicles were not.

Subsequently, an additional 2,500 miles were accumulated during which surface-ignition requirement was measured in terms of primary reference fuels. These observations were made during full-throttle accelerations from 15 TABLE IV Process composition, percent vol.:

Straight run 53 Catalytically cracked 47 Tetraethyllead content, mL/gal. 3.00 Dissolved gum, mg./100 ml. 1.00 Oxidation stability, min. 408

Total sulfur, percent wt. 0.088

1 Includes naphthenes.

Two scavenger proportions were employed. In one instance, the fuel contained 0.5 theory of bromine and 1.0 theory of chlorine as. ethylene dibromide and. ethylene dichloride r.espectively pursuantto a preferred embodiment of U. S. Patent No. 2,398,281. The other scavenger proportions used were 0.6 theory of bromine and 1.0 theory of chlorine as ethylene dibromide and ethylene dichloride respectively. These proportions fall on line CD of the figure.

Two difierent types of crankcase lubricating oils of petroleum origin were used with each of the above scavenger proportions in these tests. One oil was a bright stock-containing lubricating oil. The other crankcase lubricating oil was a wholly-distilled crankcase lubricating oil. The inspection data on these oils are shown in Table V.

TABLE V Bright stock- Wholly-discontg. oil tilled oil Crude type Mixed base- Mixed base.

Solvent.

Multigrade.

SAE 10W-20 Refining process. Type Viscosity grade Gravity, API

Pour point, Cloud point, 11.. Total sulfur, percent Weight The results of this series of road tests are shown in Table VI.

8 TABLE VI Effect of different scavenger proportions and different lubricating oils on surface ignition requirement Surlaee-ignition requirement, PRF, octane number.]

. Bright Wholly Scavenger stockdistilled eontg. oil all 0.5 theory of bromine and 1.0 theory of chlorine--.. 95. 6 89.8 0.6 theory of bromineand 1.0 theory of chlorine... 96. 2 88. 8

-Primary reference fuel.

It is clear from the data shown in Table VI that the test vehicles operated according to this invention exhibited lower surface-ignition requirements than 'the vehicles using any of the otherthree fuel-oil combinations not of this invention. Thus the ears operated according to this invention only required an 88.8 octane fuel to be free from surface ignition whereas the cars not operated according to-this invention required fuels having from 1 to 7.4 higher octane numbers. The importance of this reduced surface ignition requirement, or, to put it another way, this saving in octane numbers at the upper end of the octane scale is well known to those skilled in the art.

The cars operated according to this invention had the lowest knock requirements of all the test cars in terms of octane number as determined by measurements using primary reference fuel. In addition, the weight of combustion chamber deposits'inthe cars operated according to th'is invention was less than in the other cars.

The following specific examples illustrate antiknock fi'uids and antiknock-fuels, the relative halide proportions of which are defined by area ABCD of the figure and thusconstitute apart of this invention.

EXABIPLE I An. antiknock composition is prepared by blending together 267.4 parts of tetramethyllead, 129.6 parts of 2,3- dibromobutane and 99.0 parts of 1,2-dichloroethane. This antiknock fluid contains 0.6 theory of bromine and 1.0 theory of chlorine, represented by point 1 in the figure. The antiknock composition is blended with a premium gasoline to provide a lead concentration of '1 gram of lead pergallon.

EXAMPLE II The following ingredients are mixed: 323.5 parts of tetraethyllead, 110.3 parts of 1,l,2.-tribromoethylene and 114.4 parts of fi,;3-dichlorodiethyl .ether. The antiknock fluid contains 0.625 theory of bromine and 0.80 theory of chlorinepoint 2 in the figure. This composition is blended with petroleum. hydrocarbons of the gasoline boiling range at a concentration of 2.0 grams of lead per gallon.

EXAMPLE 111 To 323.5.parts of tetraethyllead are added 156.2 parts of mixed dibromotoluenes and 144.8 parts of n-hexyl chloride. The fluid composition contains 0.625 theory of bromine and 0.60 theory of chlorine, shown as point 3 in the figure. The antiknock fluid is blended with gasoline to a lead concentration of 6.5 grams of lead per gallon.

EXAMPLE IV 323.5 parts of tetraethyllead, 117.4 parts of ethylene dibromide and 39.6 parts of ethylene dichloride are blended together. The composition contains 0.625 theory of bromine and 0.40 theory of chl0rinepoint 4 in the figure. This composition is blended with gasoline hydr0- carbons at a concentration of 0.04 gram of lead per gallon.

EXAMPLE V The following ingredients are mixed: 379.6 parts of tetra-n-propyll'ad, 122.01 parts of ethylene dibromide and 60.5 parts of 1,2,4-trichlorobenzene. The mixture contains 0.65 theory of bromine and 0.50 theory of chlorine, shown as point in the figure. The mixture is added to gasoline to a concentration of 4.5 grams of lead per gallon.

EXAMPLE VI To 323.5 parts of tetraethyllead are added 151.2 parts of 2,3-dibrornobutane and 57,2 parts of ,6,fi'-dichlorodiethyl ether. The composition contains 0.70 theory of bromine and 0.40 theory of chlorinepoint 6 in the figure. This mixture is blended with gasoline to a concentration of 2.5 grams of lead per gallon.

EXAMPLE VII To 323.5 parts of tetraethyllead are added 140.9 parts of ethylene dibromide and 29.7 parts of ethylene dichloride. On mixing the fluid contains 0.75 theory' of bromine and 0.30 theory of chlorinepoint7 of the figure. This fluid is blended with gasoline to a concentration of 0.2 gram of lead per gallon.

EXAMPLE VIII A mixture of 435.7 parts oftetra-n-butyllead, 159.7 parts of ethylene dibromide and 28.6 parts of SLE-dichlorodiethyl ether is prepared. This mixture contains 0.85 theory of bromine and 0.20 theory of chlorine, shown in the figure as point 8. It is blended with hydrocarbons of the gasoline boiling range at a lead content of 1.5 grams of lead per gallon.

EXAMPLE rx The following mixture is prepared: 323.5 parts of tetraethyllead, 328.3 parts of n-octyl bromide and 60.5 parts of 1,2,4-trichlorobenzene. 0.85 theory of bromine and 0.50' theory of chlorine, represented by point 9 in'the figure. The mixture is blended with gasoline at a lead content of 0.75 gram of lead per gallon.

EXAMPLE X EXAMPLE XI 295.4 parts of dimethyl diethyllead is mixed with 122.1 parts of ethylene dibromide and 113.0 parts of 1,2-dichloropropane. 0.65 theory of bromine and1.0 theory of chlorine, shown in the figure as point 11. This composition is blended with gasoline to a concentration of 5.0 grams of lead per gallon.

The following specific examples represent antiknock fluid and antiknock fuel compositions of this invention which in themselves are novel and which bring about the great reduction in surface ignition rate when employed according to the invention. The relative proportions of bromine and chlorine of these compositions are defined by area EFGH of the figure.

EXAMPLE XII An antiknock fluid of this invention is prepared by blending 323.5 parts of tetraethyllead, 122.1 parts of ethylene dibromide and 59.4 parts of ethylene dichloride. This fluid contains 0.65 theory of bromine and 0.60 theory of chlorine, shown as point 12 in the figure. It is blended with gasoline so that the lead content is 4.5 grams of lead per gallon.

EXAMPLE XIII The following ingredients are mixed: 379.6 parts of This mixture contains 10 I tetraisopropyllead, 162.5 parts of mixed dibromotoluenes and 79.2 parts of ethylene dichloride. The resulting antiknouck fluid contains 0.65 theory of bromine and 0.80 theory of chlorinepoint 13 in the figure. The composi-. tion is blended with a premium gasoline to provide a lead content of 3.0 grams of lead per gallon.

1 EXAMPLE XIV To 323.5 parts of tetraethyllead are added 156.6 parts of ,B,;8-dibromodiethyl ether and 79.1 parts of 1,2-dichloropropane. The fluid contains 0.675 theory of bromine "and 0.70 theory of chlorinepoint 14 in the figure.

' This fluid is blended with petroleum hydrocarbons of the gasoline boiling range at a lead content of 5.0 grams of lead per gallon.

EXAMPLE XV The following ingredients are mixed: 323.5 parts of tetraethyllead, 141.3 parts of 1,3-dibromopropane and 72.6 parts of 1,2,4-trichlorobenzene. The resulting composition contains 0.70 theory of bromine and 0.60 theory of chlorine, point 15 in the figure. This composition is blended with gasoline at a concentration of 2.8 grams of lead per gallon.

EXAMPLE XVI To 323.5 parts of tetraethyllead are added 131.5 parts of ethylene dibromide and 69.3 parts of ethylene dichloride. The mixture contains 0.70 theory of bromine and 0.70 theory of chlorine, represented at point 16 in the figure. The mixture is added to gasoline at a concentration of 3.1 grams of leadper gallon.

EXAMPLE XVII The following ingredients are mixed: 309.4 parts of methyl triethyllead, 227.7 parts of monobromobenzene and 56.9 parts of 1,1,2-trichloroethylene. The mixture contains 0.725 theory of bromine and 0.65 theory of chlorinepoint 17 of the figure. The mixture is blended with hydrocarbons of the gasoline boiling range at a con- The resulting antiknock fluid contains centration of 1.8 grams of lead per gallon.

EXAMPLE XVIII The following ingredients are mixed: 323.5 parts of tetraethyllead, 162.0 parts of 2,3-dibromobutane and 82.6 parts of 1,4-dichlorobutane. The mixture contains 0.75 theory of bromine and 0.65 theory of chlorine, shown as point 19 in the figure. The mixture is blended with premium gasoline at a lead concentration of 2.0 grams of lead per gallon.

EXAMPLE XX To 323.5 parts of tetraethyllead are added 145.6 partsof ethylene dibromide and 72.6 parts of 1,2,4-trichlorobenzene. The mixture contains 0.775 theory of bromineand 0.60 theory of chlorine, point 20 in the figure. The mixture is blended with gasoline at a concentration of 2.7 gramsof lead per gallon.

EXAMPLE XXI To 323.5 parts of tetraethyllead are added 131.5 parts of ethylene dibromide, 24.4 parts of 2,3-dibromo-2,3-dimethyl butane and 44.5 parts of ethylene dichloride. This mixture contains 0.80 theory of bromine and 0.45 theory of chlorinepoint 21 in the figure. The mixture is blended with gasoline at a lead concentration of 3.2 grams of lead per gallon.

EXAMPLE XXII The following ingredients are blended: 323.5 parts of tetraethyllead, 112.7 parts of ethylene dibromide, 48.8

1.1 parts of 2,3-dibromo-2,3-dimethylbutane and 59.4 parts of ethylene dichloride. The resulting blend contains 0.80 theory of bromine and '0.60-theo1 'y of chlorine--point F of the figure. This blend is added to gasoline at a lead concentration of 4.0 grams or lead per gallon.

The particular 1 gasoline =used in Examples I- XXII inclusive is not critical. The gasoline can be prepared by any known refining process. To illustrate the invention, gasolines .having the following inspection data may be used if desired:

.12 bromoethane; l-phenyl-l-chloroethane; ethyl a -bromoacetate; 'diethyl-dibromomalonate; propyl-u-chlorobutyrate; =1,1-dichloro=l nitroethane; 1,1 dichloro- 2 nitroethane; 1,1-'dibromo-l-nitrobutane; 2-chloro-4-nitropentane; 2,4-dibromo 3nitropentane; l-chloro-Z-hydroxyethane; 1-bromo-3 hydroxypropane; l-bromo-S-hydroxybutane; 3-methyl-2-bromo-4 hydroxypentane; 3,4 dimethyl-Z-bromo-4-hydroxypentane; and, in general, scavengers disclosed in U. S. Patents 1,592,954; 1,668,022; 2,364,921; 2,479,900; 2,479,901; 2,479,902; 2,479,903;

Properties of representative gasolines Gasoline A B C D E F G H Process composition, percent .vol.:

Straight run 35 100 85 23 53 100 75 Catalytically cracked 40 10 21 92 47 I 25 Thermally cracked- 41 6 Reforme 15 2 Polymer 10 Butane and pentane 15 5 Dissolved gum, mg/100 ml 1. 2, 0.4 0.8 3.0 1. 5 1.0 0.5 1.0 Oxidation stability, min 795 1440 1440 660 1085 408 r 960 415 Total Sulfur, percent weight- 0. 074 0. 006 0. 023 0. 160 0. 035 0. 088 0. 005 0. 059 Gravity, API 59. 9 66. 7 68.0 59. 9 60. 2 60. 5 62. 2 64. 9 Vapor pressure, p. s. i 7. 6 6. 6 6.8 8. 6 9. 7 8. 2 8. 8 7 6 Distillation, F:

Initial evaporation 101 116 106 94 93 100 102 112 10% evaporated. 139 150 148 122 126 137 141 ,146

50% evaporated- 224 184 207 210 223 207 216' 202 90% evaporated. 328 239 260 318 358 312 296 307 Final evaporation 389 300 370 387 416 '378 354 396 Octane number:

F-l (research) 92.6 91.8 95.4 96. 6 93.2 :96.7 86.2 80.9

;FT2 (motor) 85.4 88.4 92.9 84.9 85.1 184.2 84.4 78.7 Hydrocarbon type, percent vo1.:

Paraifins 69 58 b 86 38 b 54 Olefins. 20 V 5 20 38 Aromatics 11 8 9 22 8 Naphthenes- 34 20 I Includes thermally cracked. Includes naphthenes.

The illuustrative compositions as described in Examples I-XXII inclusive may be employed in conjunction with and 2,496,983. In short, mixtures-of halogenated scavengers containing only carbon and'elements selected from any wholly-distilled lubricating oil so ,long .as it has a 40 the group consisting of hydrogen, bromine, chlorine,

boiling range asrspecified above. The following whollydistilled oils are presented .for illustrative purposes:

nitrogen and oxygen are used. Particularly preferred scavengers are halohydrocarbons,.that is, bromohydro- Properties of representative wholly-distilled lubricating oils Oil A B C -D E F G H I J K L Gravity at 60 API 30. 3 30.3 29.1 29. 5 28.8 28. 6 29. 2 31.1 29. 3 27.0 31.0 30.5 Viscosity, Saybolt:

Seconds at 100 F. 178. 8 161.8 315.3 .258. 3 309.8 314. 5 183.4 169.0 314.9 292. 335.4 201.4

Seconds at 210 F. 52. 0 48. 3 63.0 58. 63. 8 61. 9 51. 2 51.5 61. 5 59. 4 68.4 58. 9 Viscosity index- 154. 2 148. 3 138. 9 143. 5 141. 9 136. 6 148. 9 157. 8 135. 4 135. 9 144. 4 161. 5 SAE number. 5W-20 5W-20 W-30 10W-30 10W-30 10W30 5W-20 5W-20 10W-30 l0W-30 10W-30 5W-20 Pour point 30 0 -20 15 4 6 O 20 Flash point 410 410 410 390 385 410 Percent S 0. 2 0. 3 0. 3 0. 4 0. 3 0.3 0.3 0. 4 0. 3 0.3 0. 1 0.3

The scavengers which are used in formulating the antiknock fluids and antiknock fuels of this invention are organic halide compounds which react with the lead during combustion in the engine to form volatile lead halide. The halogen of these scavengers has an atomic weight between 35 and 80; that is, the active scavenging ingredient is chlorine and/ or bromine. Such scavengers include ethylene dibromide; ethylene dichloride; carbon tetrachloride; propylene dibromide; 2-ch10ro-2,3-dibrom0- butane; 1,2,3-tribromopropane; hexachloropropylene; mixed brornoxylenes; 1,4-dibromobutane; 1,4-dichloropentane; B,;3'-dibromodiisopropyl ether; 8, 3'-dichlorodi ethyl ether; trichlorobenzene; .dibromotoluenes; tert-butyl bromide; Z-methyl 2 bromobutane; 2,3,3 trimethyl 2 bromobutane; tert-butyl chloride; 2,3dimethyl-2,3-dibromobutane; 2,3-dimethyl-2,S-dibromohexane; 2-methyl 2,3 dibromobutane; 2-methyl 2,3 dichloroheptane; 2- methyl-2,4-dibromohexane; 2,4-dibromopentane; 2,5-dichlorohexane; 3-methyl-2,4-dibromopentane; l-phenyl-lcarbons and chlorohydrocarbons, having a vapor pressure from 0.1 to 250 millimeters of mercury at 50 C.

The tetraalkyllead antiknock agents which are used according to this invention are represented by such compounds as tetramethyllead, tetraethyllead, tetrapropyllead, tetrabutyllead, dimethyldiethyllead, trimethylethyllead, and the like, or mixtures'thereof. Such compounds containing from 4 to about 16 carbon atoms, one atom of lead and a plurality of lead to carbon bonds, are capable of increasing the octane quality of gasoline when employed therein in antiknock quantities-0.02 to 6.5 grams of lead per gallon. Ofsuch compounds, tetraalkyllead compounds having from 4 to about 12 carbon atoms have superior volatility characteristics from the standpoint of engineinduction and thus are preferred.

Representative compositions used according to this invention and defined by area ABCD of the figure comprise tetraethyllead, 0.6 theory of bromine as ethylene dibromide and 0.6 theory of chlorine as ethylene dichloride; tetraethyllead, 0.6 theory of bromine as mixed dibromotoluenes and 0.45 theory of chlorine as 1,2,4-trichlorobenzene; tetraethyllead, 0.70 theory of bromine as 1,6-dibromohexane and 0.30 theory of chlorine as 1,8- dlchlorooctane; tetramethyllead, 0.75 theory of bromine as 1,2,3-tribromopropane and 0.25 theory oi chlorine as 1,2-dichloroheptane; tetraethyllead, 0.70 theory of bromine as ethylene dibromide, 0.10 theory of bromine as tert-butyl bromide and 0.2 theory of chlorine as l-chloronaphthalene; tetraethyllead, 0.70 theory of bromine as ethylene dibromide, 0.10theory of bromine as 2,3-dimethyl-2,3-dibromobutane and 0.30 theory of chlorine as tert-butyl chloride; tetra-n-propyllead, 0.80 theory of bromine as 1,2,3-tribromobutane, 0.025 theory of bromine as 2,5-dimethyl-2,S-dibromohexane, 0.20 theory of chlorine as ethylene dichloride and 0.10 theory of chlorine as tert-butyl chloride; tetra-n-butyllead, 0.85 theory of bromine as mixed bromoxylenes and 0.40 theory of chlorine as benzotrichloride; methyl triethyllead, 0.825 theory of bromine as 1,4-dibromobutane and 0.50 theory of chlorine as 1,4-dichlorobutane; tetraethyllead, 0.80 theory of bromine as ethylene dibromide, 0.025 theory of bromine as 2,3-dimethyl-2,3-dibromobutane and 0.65 theory of chlorine as 1,4-dichloropentane; n-propyl triethyllead, 0.775 theory of bromine as 2,2-dibromopentame and 0.70 theory of chlorine as ethylene dichloride; tetraethyllead, 0.70 theory of bromine as 1,2-dibromo cyclohexane, 0.80 theory of chlorine as 1,2,4-trichlorobenzene and 0.10 theory of chlorine as 2,3-dimethyl-2,3- dichlorobutane; and the like. Novel compositions of this invention as defined by area EFGH comprise tetraethyllead, 0.64 theory of bromine as ethylene dibromide and 0.80 theory of chlorine as ethylene dichloride; tetraethyllead, 0.60 theory of bromine as ethylene dibromide, 0.04 theory of bromine as tert-butyl bromide and 0.65 theory of chlorine as hexachloropropylene; tetramethyllead, 0.725 theory of bromine as mixed dibromotoluenes and 0.55 theory of chlorine as 1,2-dichloroheptane; tetraethyllead, 0.70 theory of bromine as ethylene dibromide, 0.05 theory of bromine as 2,3-dimethyl-2,-3-dibromobutame and 0.60 theory of chlorine as ethylene dichloride; tetraethyllead, 0.775 theory of bromine" as 1,2-dibromoheptane and 0.45 theory of chlorine as 1,2-dichlorocyclohexane; tetraethyllead, 0.80 theory of bromine as ethylene dibromide, 0.4 theory of chlorine as ethylene dichloride and 0.1 theory of chlorine as 2,3-dimethyl-2,3- dichlorobutane; tetraethyllead, 0.75 theory of bromine as mixed dibromotoluenes and 0.70 theory of chlorine as 1,2,4-trichlorobenzene; tetraethyllead, 0.60 theory of bromine as ethylene dibromide, 0.10 theory of bromine as 2,3-dimethyl-2,3-dibromobutane and 0.80 theory of chlorine as ethylene dichloride; and the like. These compositions when made up by co-mixing the stated ingredients are antiknock fluids or composite additives which can be blended with unleaded gasoline to form the novel gasolines of this invention. As an alternative, the gasolines of this invention can be prepared by blending each of the ingredients of the anti-knock fluids with gasoline separately or in various sub-combinations.

The antiknock fluids and antiknock fuels used according to this invention may contain other ingredients, such as dyes for identification purposes; metal deactivators, such as N,N-disalicylidene-l,Z-diaminopropane, etc.; antioxidants, such as alkyl-substituted phenylene diamines, alkyl phenols, aminophenols, etc.; alcohols, such as methanol, ethanol, isopropanol, etc.; and other ingredients which do not adversely affect the nature of the engine deposits produced.

The wholly-distilled crankcase lubricating oils used in this invention may contain additives and/or blending agents. Thus, these oils may contain viscosity-index imorovers such as acrylate and methacrylate polymers; detergent-dispersants such as metallic naphthenates, -stearates, -salicylates. -petroleum sulfonates, -alkyl phenol sulfides, -wax substituted phenol derivatives, etc.; oxidation 14 and bearing corrosion inhibitors, such .as sulfurized esters, sulfurized terpenes, sulfurized olefins and paraf-v fin-wax olefins, aromatic sulfides, alkyl phenol sulfides, organic phosphites, and phosphates, dithiophosphrtes (zinc dialkyldithiophosphate), phosphorus pentasulfideterpene reactionproducts, aromatic amines, phenols and naphthols and the like; pour depressants; anti-foam agents; rusting inhibitors; dyes, metal deactivators and the like.

In summary, one aspect of the present invention relates to an improved method of operating a spark-ignition internal-combustion engine wherein gasoline is introduced into a combustion chamber of an engine and ignited therein, and the products of combustion act upon a piston thereby producing a driving force, the particular improvement comprising (I) introducing into said combustion chamber along with the gasoline (A) an antiknock quantity of a tetraalkyllead antiknock agent and (B) a mixture of a bromine-containing scavenger and a chlorine-containing scavenger, said scavenger being capable of reacting with the lead during combustion in the engine to form volatile lead halides, the proportions of bromine and chlorine of said mixture initially being defined by the area AB,CD of the figure, and (II) concurrently introducing into said combustion chamber a small amount of a wholly-distilled crankcase lubricating oil distilling within the range of from about 550 to about 900 F. at atmospheric pressure according to ASTM Test Procedure D-1160-52T. Another aspect of this invention relates to the provision of novel antiknock fluids and leaded gasolines, the scavenger proportions of which are defined by area EFGH of the figure.

We claim:

1. In the method of operating a spark-ignition internal-combustion engine wherein gasoline is introduced into a combustion chamber of the engine and ignited therein, and the products of combustion act upon a piston thereby producing a driving force, the improvement which comprises (I) introducing into said combustion chamber along with the gasoline (A) an antiknock quantity of tetraalkyllead antiknock agent and (B) a mixture of a bromine-containing scavenger and a chlorine-containing scavenge said scavengers being capable of reacting with the lead during combustion in the engine to form volatile lead halides, the proportions of bromine and chlorine of said mixture initially being defined by the area ABCD of the figure, and (II) concurrently introducing into said combustion chamber a small amount of a wholly-distilled crankcase lubricating oil distilling within the range of from about 550 to about 900 F. at atmospheric pressure according to ASTM Test Procedure D-l-52T.

2. The method of claim 1 further characterized in that said mixtureof a bromine-containing scavenger and a chlorine-containing scavenger is a mixture of a bromohydrocarbon compound and a chlorohydrocarbon compound.

3. The method of claim 1 further characterized in that said mixture of a bromine-containing scavenger and a chlorine-containing scavenger is a mixture of ethylene dibromide and ethylene dichloride.

4. In the method of operating a spark-ignition internal-combustion engine wherein gasoline is introduced into a combustion chamber of the engine and ignited therein, and the products of combustion act upon a piston thereby producing a driving force, the improvement which comprises (1) introducing into said combustion chamber along with the gasoline (A) an antiknock quantity of tetraethyllead and (B) a mixture of ethylene dibromide and ethylene dichloride, the proportions of bromine and chlorine of said mixture being defined by the area ABCD of the figure, and (II) concurrently introducing into said combustion chamber a small amount of a wholly-distilled crankcase lubricating oil distilling within 15 the range of from about 550 to about 900 F. at atmospheric-pressure "according to AS'IM "Test "Procedure D-1160-52T.

5. The method -of claim 4 further characterized in that the proportions of bromine and chlorine of said mixture 'of ethylene dibromide and ethylene diehloride are initially 0.6 theory of bromine as ethylene dibromide and 1:0 'theoryof'ehlorineas ethylene dichloride.

iReferences'Cited in the file of this patent 

